Cells become cancerous when their genotype or phenotype alters in a way that there is uncontrolled growth that is not subject to the confines of the normal tissue environment. One or more genes is mutated, amplified, deleted, overexpressed or underexpressed. Chromosome portions can be lost or moved from one location to another. Some cancers have characteristic patterns by which genotypes or phenotypes are altered.
Many genes have mutations which are associated with cancer. Some genes have multiple sites where mutations can occur. Many cancers have mutations in and/or mis-expression of more than one gene. Gene mutations can facilitate tumor progression, tumor growth rate or whether a tumor will metastasize. Some mutations can affect whether a tumor cell will respond to therapy.
A variety of agents treat cancers. Cancers of the blood and bone marrow often are treated with steroids/glucocorticoids, imids, proteasome inhibitors and alkylating agents. Cancers of other tissues often are treated with alkylating agents, topoisomerase inhibitors, kinase inhibitors, microtubule inhibitors, angiogenesis inhibitors or other agents. Some patients respond to one therapy better than another, presenting the potential for a patient to follow multiple therapeutic routes to effective therapy. Valuable time early in a patient's treatment program can be lost pursuing a therapy which eventually is proven ineffective for that patient. Many patients cannot afford the time for trial-and-error choices of therapeutic regimens. Expedient and accurate treatment decisions lead to effective management of the disease.